Prediction Models for Serious Bacterial Infection in Infants Up to 90 Days of Age

In a decade-long retrospective study at a tertiary center, predictive models for serious bacterial infections (SBIs) in febrile infants <90 days were devised. Among 1250 infants, SBIs were found in 18.4% of those <29 days and 15.1% of those aged 29 to 89 days. Elevated absolute neutrophil count (ANC) (>7500 mm³) and C-reactive protein (CRP) (>3 mg/dL) were risk factors in both groups, with viral-like illness in family members being protective. Diarrhea was a risk factor in the younger group and protective in the older group, while female sex was a risk factor in the older group. The "NeoSBIscore," incorporating these factors with signs of focal infection and abnormal urinalysis, exhibited 94.7% sensitivity and 97.0% negative predictive value (NPV) in <29 days and 92.8% sensitivity and 94.7% NPV in older infants, effectively detecting SBI with higher thresholds of widely available biomarkers and comprehensive clinical details. This tool aids in SBI risk assessment.